Heretofore, in a charged-particle beam device represented by a scanning electron microscope, for example, by tilting the sample stage to the left and to the right to obtain a tilted image for the left eye and a tilted image for the right eye, to display a 3D (stereoscopic) observation image in the crossover method, the parallel method, or the anaglyph method using red-cyan glasses. Also, to obtain the left and right-tilted observation images as the source of the 3D observation image, in place of mechanical control to tilt the sample stage, there is conducted operation to tilt charged-particle beams irradiated on the sample by electromagnetic control.
For example, Patent literature 1 and 2 describe an operation to obtain observation images associated with different angles by tilting charged-particle beams. That is, charged-particle beams are controlled to irradiate on the outside of the axis of the objective lens and are tilted by use of the focusing action of the objective lens.
Further, Patent literature 3 and 4 disclose adjusting means to appropriately adjust the optical system when charged-particle beams are tilted. For example, Patent literature 3 describes an operation in which a non-tilted observation image (top-down image) is obtained and is formed into a template; thereafter, when obtaining a tilted observation image, pattern matching is conducted between the tilted observation image and the template, to thereby conduct image matching and astigmatism correction and the focus adjustment. Moreover, Patent literature 4 discloses a technique in which combinations of a plurality of lenses and the behavior of charged-particle beams when they are irradiated on the outside of the axis of the objective lens are analytically solved, and aberration taking place when charged-particle beams are tilted to irradiate on the sample is comprehensively cancelled by optical constituent components.
Further, Patent literature 5 discloses a technique in which the tilt of charged-particle beams is controlled for each line to obtain the left-tilted and right-tilted images at the same time and the obtained left and right-tilted images are displayed on a 3D display device, to thereby conduct 3D observation.